Transcript Examination of A Mammalian Lung

Why do we
breathe?
If you were to design an
efficient breathing system,
what would the
requirements be?
RESPIRATORY
SYSTEM
1.External respiration
2.Internal respiration
RESPIRATION
External
Between environment
and lungs
Internal
Between blood and cell
http://activity.ntsec.gov.tw/lifeworld/english/content/body_cc4.html
RESPIRATORY
TRACT
Bronchi
Examination of A Mammalian Lung
A.Read instructions in the handout.
Dissect and observe the lung.
B.Note down observations in your
handout.
C.Answer the questions (refer to
handout) in your notebook.
Procedure:
1. Locate the trachea. What do you observe about its structure? What other structures
are found near the trachea?
2. Follow the trachea down to locate the right and left bronchus. Note size difference
between trachea and bronchi.
3. Feel the texture of the lungs. Gently squeeze them. What makes them feel like this?
Compare the texture of the lung tissue with the trachea. Why are they built of
different tissue?
4. Are the two lungs of the same size?
5. What do the lungs contain? You may not be able to identify specific structuresremember the alveoli are very small (however, when spread out ,they cover the size
of a tennis court. THINK!! Surface area). Describe the tissue.
6. Locate the position of the heart- you will see the severed arteries and veins. Do you
think there is a relationship between the large tube lying between the lungs and the
severed arteries/veins? Can you name this tube?
7. Look more carefully at the cut edge of the lung. Examine it carefully. Is there a
structure that covers the lungs?
8. Gently insert the rubber tubing down the trachea and one of the bronchi and
gently
blow into the tubing, watching for the lung to inflate a little. Do not over inflate.
Notice the elasticity of the tissue. How is the lung designed to perform its behavior?
DISCUSSION QUESTIONS:
1. Explain how the design of the following structures relates to its behavior.
a. Why is the trachea made up of rings of cartilage?
b. What is the main difference between the esophagus and the trachea?
c. Do the bronchi have cartilage reinforcing? Explain.
2. The lung is an ideal structure for gas exchange in land-based organisms.
Describe the feel and appearance of the lung tissue. How is its shape
related to its behavior? What other features make the lung efficient in its
work?
3. One function of the small intestine is to absorb food. One function of the lungs
is to absorb oxygen. Point out the basic similarities in these two structures
that help to speed up the process of absorption.
4. Trace the pathway of air as it enters the nasal passages to the lungs and back.
5. Name the small air sac where O2 and CO2 are exchanged. Describe changes
in blood composition as these gases pass through these structures in the
lungs.
TUBULAR
PASSAGEWAY
FOR AIR
Bronchioles
TRACHEA